Assuming multi-cellular life exists elsewhere in the universe, what do you think it looks like?

[rousseau]

I've always thought that the human imagination has painted 'aliens' in a weird picture. I figure if life does exist elsewhere in the universe it's probably going to look very similar to life on earth.

What do you think?

 

[dystopian]

It very much depends on the conditions of wherever they evolved. When we look at Earth, there are vast differences in what life looks based on that criteria; the lifeforms that evolved/exist in environments we are familiar with look "normal" to us; whereas others can look mindbendingly alien. Fish that exist near to the surface (an environment we're familiar with even if it isn't our own) tend to look pretty normal; deep sea creatures on the other hand, not so much.

If alien life evolved on the surface of a world with a similar atmosphere and surface conditions to our own, yeah it's probably going to look more similar to life on earth; although there'd still be distinct differences. A world as teeming with life as our own might for instance have life that looks superficially like our own, but rather than 4 limbs being the standard form for large creatures, it could be some other number. Life that evolved on a world very different from our own though, all bets are off.

 

[ryan]

I've always thought that the human imagination has painted 'aliens' in a weird picture. I figure if life does exist elsewhere in the universe it's probably going to look very similar to life on earth.

What do you think?

Over 1 billion years, life on Earth has almost every imaginable type of appearance. Not even a science fiction writer could even dream up some of the deep-sea life forms that exist. From plants to insects to animals that have existed or exist today, I don't think I could be surprised by any alien appearance. See, https://images.search.yahoo.com/sea...deep-sea+creatures&fr=yfp-t-328-s&fr2=piv-web , and it should be hard to limit what alien life could look like.

So my answer is anything.

 

[dystopian]

I've always thought that the human imagination has painted 'aliens' in a weird picture. I figure if life does exist elsewhere in the universe it's probably going to look very similar to life on earth.

What do you think?

Over 1 billion years, life on Earth has almost every imaginable type of appearance. Not even a science fiction writer could even dream up some of the deep-sea life forms that exist. From plants to insects to animals that have existed or exist today, I don't think I could be surprised by any alien appearance. See, https://images.search.yahoo.com/sea...deep-sea+creatures&fr=yfp-t-328-s&fr2=piv-web , and it should be hard to limit what alien life could look like.

So my answer is anything.

The problem with this thinking is pretty much what the OP is about. The thing is that given similar conditions; we should expect similar life. There's only so many forms life could conceivably take under a given set of environmental conditions. There's a reason we don't see giant nine legged landsquids walking about; all large animals in a given environmental niche on earth look broadly similar, and while this is in part due to common ancestry, it's also just because that general archetype is just the most likely form evolution under those circumstances arrives at. Humans and giraffes look superficially different, but really they're absurdly similar if you look at them objectively. The broad strokes are the same. And what Rousseau is saying is that we should expect the same rough broadstrokes applied on an alien world, to which I would add the criterion; "so long as said world is similar enough to earth". The details might be different, but we'd probably not recoil in existantial horror from how different the aliens are to us.

 

[steve_bnk]

Look at the variety on Earth.

Looking at reality from the insect scale and we have a universe of strange beasts.

Ditto at the marine scale if you look at all of it including the marine life not commonly seen.

Life existing at toxic undersea volcanic vents.

look at the artist renderings of ancient sea life. Some pretty ferocious creatures.


If evolution is a constant, then life will evolve to its environment and resources.

 

[ryan]

Over 1 billion years, life on Earth has almost every imaginable type of appearance. Not even a science fiction writer could even dream up some of the deep-sea life forms that exist. From plants to insects to animals that have existed or exist today, I don't think I could be surprised by any alien appearance. See, https://images.search.yahoo.com/sea...deep-sea+creatures&fr=yfp-t-328-s&fr2=piv-web , and it should be hard to limit what alien life could look like.

So my answer is anything.

The problem with this thinking is pretty much what the OP is about. The thing is that given similar conditions; we should expect similar life. There's only so many forms life could conceivably take under a given set of environmental conditions. There's a reason we don't see giant nine legged landsquids walking about; all large animals in a given environmental niche on earth look broadly similar, and while this is in part due to common ancestry, it's also just because that general archetype is just the most likely form evolution under those circumstances arrives at. Humans and giraffes look superficially different, but really they're absurdly similar if you look at them objectively. The broad strokes are the same. And what Rousseau is saying is that we should expect the same rough broadstrokes applied on an alien world, to which I would add the criterion; "so long as said world is similar enough to earth". The details might be different, but we'd probably not recoil in existantial horror from how different the aliens are to us.

Please look through the pictures in the link I gave in my last post. These creatures look objectively different - it is boggling.

 

[barbos]

I've always thought that the human imagination has painted 'aliens' in a weird picture. I figure if life does exist elsewhere in the universe it's probably going to look very similar to life on earth.

What do you think?

I agree.
Excluding artificial forms of life we are pretty much stuck with carbon+water based life.
As for external appearance what we have now is a result of billion years of evolution and it is simply the best design.
I am ignoring minor things of course. In these popular science documentaries they always try to imagine weird lifeforms designs but they forget about evolution. At best that thing can be created to survive in certain rather inhospitable environment, but it will never evolve to that.
as for intelligent life then too, I expect them to pretty much look like us - bi-pedal apes of roughly our size.

 

[Jokodo]

Over 1 billion years, life on Earth has almost every imaginable type of appearance. Not even a science fiction writer could even dream up some of the deep-sea life forms that exist. From plants to insects to animals that have existed or exist today, I don't think I could be surprised by any alien appearance. See, https://images.search.yahoo.com/sea...deep-sea+creatures&fr=yfp-t-328-s&fr2=piv-web , and it should be hard to limit what alien life could look like.

So my answer is anything.

The problem with this thinking is pretty much what the OP is about. The thing is that given similar conditions; we should expect similar life. There's only so many forms life could conceivably take under a given set of environmental conditions. There's a reason we don't see giant nine legged landsquids walking about; all large animals in a given environmental niche on earth look broadly similar, and while this is in part due to common ancestry, it's also just because that general archetype is just the most likely form evolution under those circumstances arrives at. Humans and giraffes look superficially different, but really they're absurdly similar if you look at them objectively. The broad strokes are the same. And what Rousseau is saying is that we should expect the same rough broadstrokes applied on an alien world, to which I would add the criterion; "so long as said world is similar enough to earth". The details might be different, but we'd probably not recoil in existantial horror from how different the aliens are to us.

Humans and giraffes are absurdly similar because they share an absurdly recent common ancestry - If you map the history of life on Earth onto a year, our lines diverged on Christmas Eve. Even if it is true that the main phyla on an alien world would have similar Bauplans to the main phyla on earth today, (and even that is questionable - a number of phyla that emerged during the Cambrian explosion seem to have gone extinct quickly thereafter, and it's probably more luck than anything else that the chordates weren't among them), it could still easily be the case that their eyuivalent of large land animals would be a derivative of the (equivalent of) Crustaceans, or Annelids, or Molluscs.

Yes, there is a reason we don't see landsquids walking about: It's that vertebrates were already firmly established in what might have otherwise been their niche. It's not that the cephalopod or mollusc Bauplan or body architecture is inherently incompatible with fulfilling that niche under any circumstances, at least not obviously. If you want to argue that it is, you'll have to come up with something better than "we don't see any landsquids, do we?"

 

[braces_for_impact]

Most lifeforms show some symmetry though. I might expect alien life to be similar that way, it just seems...necessary or pragmatic for ease of movement, cell division, etc.

 

[Jokodo]

I've always thought that the human imagination has painted 'aliens' in a weird picture. I figure if life does exist elsewhere in the universe it's probably going to look very similar to life on earth.

What do you think?

I agree.
Excluding artificial forms of life we are pretty much stuck with carbon+water based life.
As for external appearance what we have now is a result of billion years of evolution and it is simply the best design.
I am ignoring minor things of course. In these popular science documentaries they always try to imagine weird lifeforms designs but they forget about evolution. At best that thing can be created to survive in certain rather inhospitable environment, but it will never evolve to that.

Except that, in the history of Earth alone, very different animals have occupied more or less in the same environments. Since the Cretacean, bony fish, and specifically  perciformes (an order that only arose in the late Cretacean and comprises 40% of all living fish species) have taken niches that where previously occupied by ammonites, and before them by trilobites.

as for intelligent life then too, I expect them to pretty much look like us - bi-pedal apes of roughly our size.

I seem to have a deja vu. Didn't we have this discussion before over on the old board? I seem to remember that you explicitly refused to provide any rational argument for your claim then.

 

[Jokodo]

Please look through the pictures in the link I gave in my last post. These creatures look objectively different - it is boggling.

What does "look objectively different" mean? Either they are objectively different, or they look different, which is by definition a subjective attribute. Since almost half of the creatures depicted are fish like us, I assume you mean the latter.

 

[barbos]

I agree.
Excluding artificial forms of life we are pretty much stuck with carbon+water based life.
As for external appearance what we have now is a result of billion years of evolution and it is simply the best design.
I am ignoring minor things of course. In these popular science documentaries they always try to imagine weird lifeforms designs but they forget about evolution. At best that thing can be created to survive in certain rather inhospitable environment, but it will never evolve to that.

Except that, in the history of Earth alone, very different animals have occupied more or less in the same environments. Since the Cretacean, bony fish, and specifically  perciformes (an order that only arose in the late Cretacean and comprises 40% of all living fish species) have taken niches that where previously occupied by ammonites, and before them by trilobites.

I don't consider these sufficiently different. On the scale of great variaty we already have they are very similar.
I mean I expect to see trilobite like things on every sufficiently life rich planet.

as for intelligent life then too, I expect them to pretty much look like us - bi-pedal apes of roughly our size.

I seem to have a deja vu. Didn't we have this discussion before over on the old board? I seem to remember that you explicitly refused to provide any rational argument for your claim then.

No, I did provide rational argument. You merely failed to provide counter-argument.

 

[dystopian]

Yes, there is a reason we don't see landsquids walking about: It's that vertebrates were already firmly established in what might have otherwise been their niche. It's not that the cephalopod or mollusc Bauplan or body architecture is inherently incompatible with fulfilling that niche under any circumstances, at least not obviously. If you want to argue that it is, you'll have to come up with something better than "we don't see any landsquids, do we?"

For one thing, you can't get an invertebrae out of water the size of a human of a human or up; it would collapse under its own weight and would not be able to do much more than flail about ineffectually. This isn't a matter of 'oh if only the invertebrates had filled that niche first"; it's a matter of simple physics. That's what I'm talking about; there is always going to be an optimum range of biological configurations for any given environment. Now in theory, you could have a creature somewhat similar to earth invertebrates with the right set of evolutionary adaptations occupying a land niche... but only so long as it evolved in a biological vacuum,. and it wouldn't be very effective and would be screwed as soon as something better came along.

 

[rousseau]

I agree.
Excluding artificial forms of life we are pretty much stuck with carbon+water based life.
As for external appearance what we have now is a result of billion years of evolution and it is simply the best design.
I am ignoring minor things of course. In these popular science documentaries they always try to imagine weird lifeforms designs but they forget about evolution. At best that thing can be created to survive in certain rather inhospitable environment, but it will never evolve to that.

Except that, in the history of Earth alone, very different animals have occupied more or less in the same environments. Since the Cretacean, bony fish, and specifically  perciformes (an order that only arose in the late Cretacean and comprises 40% of all living fish species) have taken niches that where previously occupied by ammonites, and before them by trilobites.

as for intelligent life then too, I expect them to pretty much look like us - bi-pedal apes of roughly our size.

I seem to have a deja vu. Didn't we have this discussion before over on the old board? I seem to remember that you explicitly refused to provide any rational argument for your claim then.

They are also moving along an evolutionary line while in similar environments. So we could assume that varying species are able to live in the same environment, but a similar evolutionary line might progress in a similar planet.

Another interesting thought is: what is the extreme of divergence from an earth-like planet that could still hold life? What would that life look like?

 

[dystopian]

Another interesting thought is: what is the extreme of divergence from an earth-like planet that could still hold life? What would that life look like?

In terms of sci depictions of alien life; I always liked The Mist; it's about lifeforms from a parallel earth that split off from our timeline a long time ago. They're pretty different as such, but still look entirely like something that could have evolved on earth if distant history had just been a little different.

 

[Jokodo]

Except that, in the history of Earth alone, very different animals have occupied more or less in the same environments. Since the Cretacean, bony fish, and specifically  perciformes (an order that only arose in the late Cretacean and comprises 40% of all living fish species) have taken niches that where previously occupied by ammonites, and before them by trilobites.

I don't consider these sufficiently different. On the scale of great variaty we already have they are very similar.
I mean I expect to see trilobite like things on every sufficiently life rich planet.

as for intelligent life then too, I expect them to pretty much look like us - bi-pedal apes of roughly our size.

I seem to have a deja vu. Didn't we have this discussion before over on the old board? I seem to remember that you explicitly refused to provide any rational argument for your claim then.

No, I did provide rational argument. You merely failed to provide counter-argument.

So you say that trilobites, ammonites, and fish are sufficiently similar that they count as one and the same "best design", but when it comes to intelligent life, you are confident expecting them to be something much more specific - "be-pedal apes" of a specific size range.

That's not rational.

 

[barbos]

Another interesting thought is: what is the extreme of divergence from an earth-like planet that could still hold life? What would that life look like?

you are stuck with rocky planet of roughly Earth size.
Mars is too small to hold atmosphere for sufficiently long time.
Heavier planets will not work for intelligent life. I mean there will be size limit for surface creatures.

 

[Jokodo]

Except that, in the history of Earth alone, very different animals have occupied more or less in the same environments. Since the Cretacean, bony fish, and specifically  perciformes (an order that only arose in the late Cretacean and comprises 40% of all living fish species) have taken niches that where previously occupied by ammonites, and before them by trilobites.

as for intelligent life then too, I expect them to pretty much look like us - bi-pedal apes of roughly our size.

I seem to have a deja vu. Didn't we have this discussion before over on the old board? I seem to remember that you explicitly refused to provide any rational argument for your claim then.

They are also moving along an evolutionary line while in similar environments.

Not necessarily - the trilobites fell victim to a mass extinction event that killed of some 95% of species at the time.

So we could assume that varying species are able to live in the same environment, but a similar evolutionary line might progress in a similar planet.

You're dangerously close to teleological thinking here.

 

[barbos]

I don't consider these sufficiently different. On the scale of great variaty we already have they are very similar.
I mean I expect to see trilobite like things on every sufficiently life rich planet.

as for intelligent life then too, I expect them to pretty much look like us - bi-pedal apes of roughly our size.

I seem to have a deja vu. Didn't we have this discussion before over on the old board? I seem to remember that you explicitly refused to provide any rational argument for your claim then.

No, I did provide rational argument. You merely failed to provide counter-argument.

So you say that trilobites, ammonites, and fish are sufficiently similar that they count as one and the same "best design", but when it comes to intelligent life, you are confident expecting them to be something much more specific - "be-pedal apes" of a specific size range.

That's not rational.

As far as ocean concerned, evolution has tried virtually everything with great success.
As for intelligent species then there is only one such specie on planet earth, ask yourself why?
you really expect birds for example to evolve true human-like intelligence? why would the do that?

 

[Rhea]

Yes, there is a reason we don't see landsquids walking about: It's that vertebrates were already firmly established in what might have otherwise been their niche. It's not that the cephalopod or mollusc Bauplan or body architecture is inherently incompatible with fulfilling that niche under any circumstances, at least not obviously. If you want to argue that it is, you'll have to come up with something better than "we don't see any landsquids, do we?"

Good point. Evolution ALSO depends on who else occupied a niche when something emerges. That's often forgotten. We're not the "best" design, only the best in those exact circumstances. Speciation itself directly shows that in different circumstances, something different will emerge. And those circumstances include not only the environment, but also the competition. If the competition changes, the "best" form changes even in a stable environment. And I put "best" in quotes because it's not always the most efficient form, it's just what out takes the current instantaneous conditions. Like the race driver who is not the fastest, but has the luck to navigate the oil-spill without spinning because he was in the back of the pack and missed the pile-up. He wins, but not because he was "better" but because he got lucky in where he was positioned when something happened to the others.